Biomedical subjects

H H Horch

Publications and source records attributed to H H Horch.

At least 19 recordsLinked to original sources

PubMed2002

[Surgical vs. conservative therapy of diacapitular and high condylar fractures with dislocation. A comparison between MRI and axiography].

AIMS: At present the discussion about the correct management of high condylar and diacapitular fractures has been reopened. The aim of the present prospective study was to evaluate the role of condylar mobility, disk mobility, and vertical dimension regarding the postoperative functional outcome after open reduction and osteosynthesis compared to nonsurgical treatment. METHODS: Since 1993 a total of 130 high condylar and diacapitular fractures have been treated by open reduction and osteosynthesis. Thirty-nine subjects with 51 fractures classes V and VI according to Spiessl and Schroll (surgical treatment, ST) were assessed postoperatively (mean 24 months) including magnetic resonance imaging (MRI) and axiography. Sixteen conservatively treated fractures served as a reference (conservative treatment, CT). RESULTS: Surgically treated temporomandibular joints presented a better condylar mobility (11.4 mm after ST, 5.9 mm after CT) and a less remarked loss of vertical ramus height (1.6 mm after ST, 5.4 mm after CT). Conservatively treated high condylar fractures formed a nearthrosis with the articular eminence in an anteromedial malposition (x axis 6.9 mm, y axis 10.3 mm). Disk mobility was reduced in both groups (3.8 mm after CT, 5.8 mm after ST), with major interindividual variations after ST. Significant correlations were found in the surgically treated group between axiographic limitations and limitations of disk mobility (p < 0.01) or periarticular scar formations (p < 0.01). Helkimo indices after ST (31% symptom free, 67% light symptoms < 5 points) were clearly superior (p < 0.01) to conservative treatment, with 63% of the subjects presenting craniomandibular symptoms > 5 points. CONCLUSIONS: According to the functional results observed, high condylar and diacapitular fractures will profit by open reduction and osteosynthesis. Only effective surgical procedures can preserve both disk mobility and vertical ramus height.

Adult↗

PubMed2002

[Speech outcome after simple and multiple cleft palate operations].

OBJECTIVES: If the primary palatal closure in a patient with cleft lip and palate is unsuccessful, defects such as palatal fistulas and a short velum have to be corrected by secondary operations. It is an informal belief among surgeons that these reoperations can have detrimental effects on the patients' nasal resonance and articulation. It was our aim to critically evaluate the validity of this belief. MATERIAL AND METHODS: One hundred and twenty-four patients with cleft lip and palate were divided into three groups. The 70 patients in group 1 had only undergone a primary palatal closure operation. The 33 patients in group 2 had undergone one or more palatal reoperations. The 21 patients in group 3 had undergone an additional pharyngeal flap operation. Resonance and articulation were evaluated perceptually. Nasalance was assessed with the NasalView system, and the mean speech rate was analyzed with the MODIAS software. RESULTS: There were no significant differences for any of the speech measures between groups 1 and 2. Patients in group 3 had significantly worse results for all speech measures. CONCLUSIONS: The speech outcomes for patients with multiple palatal reoperations were no different from those of patients with single palatal closure operations. The pharyngeal flap operation did not lead to sufficient improvements in the speech of the patients in group 3.

Adolescent↗

PubMed2002

Investigation on plasma immersion ion implantation treated medical implants.

In this work the biocompatibility of osteosynsthesis plates treated with plasma immersion ion implantation (PIII) was tested using a rat model. Small rods (Ø 0.9 mm, and length 10 mm) prepared from different materials-pure Ti, anodised Ti, and two NiTi alloys (SE 508, and SM 495)-were implanted with oxygen by PIII to form a rutile surface layer and subsequently inserted into rat femurs, together with a control group of untreated samples. The results of the biomechanical tests correlate with the histological results, and show that plasma immersion ion implantation leads to an increase of biocompatibility and osseointegration of titanium and NiTi, albeit no improvement of the (bad) biocompatibility of the anodised Ti. Despite the layer thickness of up to 0.5 microm a strong influence of the base material is still present.

Animals↗

PubMed2001

[Stress analysis of the human mandible in standard trauma situations with numerical simulation].

For the stress analysis of the human mandible a flexible simulation concept basing on finite element-method has been developed. One of the main issues is the prediction of fractures as a consequence of known forces as well as the forensic reconstruction of the traumatologic situation. At first, the individual geometry was reconstructed by 3D-CT-Scans. To reduce the simulation efforts, for the time being the anisotropic structural mechanics of the jaw bone was neglected in favour of an homogeneous and isotropic material law. Assuming the Von-Mises-Stress as a failure indicator the results of the simulations were in good agreement with typical traumatologic situations. For further validation of the model, a real failure case, shown on a radiograph of a injured human mandible with three fractures, was simulated and, by this, the real incident was reconstructed. Reasonable planned extensions of the actual simulation concept have the regard on the nerve channel, the temporomandibular joint's function, the paradontal apparatus and the individual mechanical properties of the bone.

Biomechanical Phenomena↗

PubMed2001

Levatorplasty, a new technique to treat hypernasality: anatomical investigations and preliminary clinical results.

BACKGROUND: Velopharyngoplasty is the most commonly used operative technique for the treatment of velopharyngeal insufficiency. By attaching a posterior pharyngeal flap to the velum, a nonphysiological situation is created in the upper airway. PURPOSE: The aim of this investigation was to find a new surgical approach to physiological reconstruction of the velopharyngeal sphincter. MATERIAL: Anatomical investigations were performed in four cadavers. From this study a new surgical technique was developed and called 'levatorplasty': the musculus longus capitis was taken to create a new muscular loop leading to (a) an augmentation of the posterior wall, (b) a medial shift of the lateral pharyngeal wall; and (c) stretching of the velum posteriorly. Thus, the velopharyngeal space was reduced and a physiological closure of the nasal airway space could be obtained. STUDY DESIGN: The levatorplasty was employed in nine cleft palate patients with velopharyngeal insufficiency. Pre- and postoperatively the velopharyngeal closure was evaluated by phonetic and radiological examination. RESULTS: The operation was easily performed without major complications. A concentric constriction with decrease of the velopharyngeal space was achieved and a definitive decrease of nasalance and hypernasality resulted. CONCLUSION: Long-term follow-ups have to verify whether these results will be stable. They also have to be compared with functional improvements following velopharyngoplasty or pharyngoplasty. Of special interest will be evaluation of the altered mobility of the lateral pharyngeal walls.

Adolescent↗

PubMed2000

[Position and mobility of the articular disk after surgical management of diacapitular and high condylar dislocation fractures of the temporomandibular joint].

Magnetic resonance imaging (MRI) assessment of traumatized temporomandibular joints (TMJ) usually focuses on disc position, defining regular joint function by normal, excentric or displaced disc position. So far, there are only few reports regarding disc position after open reduction of diacapitular or high condylar fractures of the TMJ with dislocation. The aim of the present study was to evaluate the role of the disc as regards postoperative functional outcome by electronic axiographic recordings of condylar movements and MRI, displacement of the disc and lesions of TMJ soft tissues being frequent in this type of mandibular fractures. A total of 30 subjects with 37 condylar fractures in whom osteosynthesis was performed using a preauricular approach were imaged postoperatively (mean 24 months) with a 1.5-Tesla MRI system to determine, (a) the position of the disc, (b) the range of mobility of the disc and (c) condylar mobility in closed and open mouth position, comparing fractured sides (FS) vs nonfractured sides (NFS). Linear movements between the two jaw positions in the sagittal plane were measured by superimposing transparencies. The results indicate: (1) more than 70% of the discs (FS) were found to be in normal position; there was no disc displacement without reduction. However, these data stood in contrast to severe limitations of the axiographic tracings as presented by almost 30% of the subjects. (2) Significant correlations were found between fixed (alpha = 0.05) or highly immobilized (alpha = 0.01) discs and axiographic limitations, suggesting disc mobility to be a valuable parameter for assessment of the postoperative functional outcome.

Adult↗

PubMed2000

[A modular software concept for individual numerical simulation (FEM) of the human mandible].

A new modular software concept for individual numerical simulation of the human mandible using the finite element method (FEM) is presented. The main task is an individual analysis of regional stress and stress-compatibility on the basis of computed tomographic data in individual patients. Simulation should, however, also be possible in parallel with biomechanical experiments, or for further research projects. For this purpose, rapid and uncomplicated generation of the FEM model, easy modification of input data, and short computation times are required. Practical use in the clinical setting makes appreciable additional demands on the individual software components.

Biomechanical Phenomena↗

PubMed2000

Nasalance distance and ratio: two new measures.

OBJECTIVES: Mean nasalance in speakers with perceptually normal nasal resonance can differ in magnitude considerably. In addition, categorizations of speech based on nasalance scores may not agree with perceptual judgments. To overcome this limitation, we evaluated two new simple measures derived from mean nasalance data: the nasalance distance (range between maximum and minimum nasalance) and the nasalance ratio (minimum nasalance divided by maximum nasalance). SETTING: Department of Oral and Maxillofacial Surgery, University of Technology, Munich, Germany. SUBJECTS: The sample consisted of 133 cleft lip and palate patients with normal nasal resonance or varying degrees of hypernasality. PROCEDURES: Oral and nasal acoustic measurements were made using the NasalView system. Nasalance distance and nasalance ratio were calculated for five non-nasal and three nasal sentences from the modified Heidelberg Rhinophonia Assessment Form. RESULTS: Optimum cutoffs were derived from receiver-operating characteristics. Results for the sentence stimuli ranged from 64.4% to 89.6% sensitivity and from 91.2% to 94.1% specificity. When the analysis was limited to only one nonnasal and one nasal sentence, results ranged from 79.7% to 87.5% sensitivity and from 88.2% to 97.1% specificity. CONCLUSIONS: We conclude that the two new measurements are valuable in routine clinical examinations. Nasalance distance and ratio derived from sentence stimuli are two useful and easily applicable measures that can be used to supplement the nasalance mean value.

Adolescent↗

PubMed1999

[Quantitative diagnosis of hypernasality in cleft lip and palate patients by computerized nasal quality assessment].

In patients with cleft lip and palate (CLP), the assessment of velopharyngeal morphology and function and the quantitative analysis of perceptual consequences of velopharyngeal insufficiency are of major importance regarding the effective planning of velopharyngoplasties for speech improvement. The NasalView, a new instrument for the objective assessment of rhinophonia, is presented. The NasalView measures nasalance, the relative sound pressure level of the nasal signal in speech, expressed as a percentage. In order to evaluate the effectiveness of the computerised measurement of nasalance, 156 patients with surgically treated CLP were examined. The NasalView differentiated with high sensitivity and specificity between patients with normal nasal resonance and patients with varying degrees of hypernasality. To illustrate the importance of the NasalView for making the decision for a velopharyngoplasty, a single case is presented.

Adolescent↗

PubMed1999

[New aspects for indications of surgical management of intra-articular and high temporomandibular dislocation fractures].

Conservative treatment of TMJ condylar fractures (groups V and VI according to Spiessl and Schroll 1972) often shows poor clinical results. This follow-up study was designed to objectify the benefits of an operative procedure by electronic computer-assisted recording of condylar movements. Sixty-three individuals with a total of 77 condylar fractures (42 diacapitular fractures, 35 high condylar process fractures) underwent surgery over a preauricular approach. Osteosynthesis was performed according to the intraoperative site either by PDS pins, titanium lag screws, microplates, miniplates or a combination of these materials. Radiological controls showed a considerable loss of height of the condylar process in the diacapitular group of fractures affecting the lateral condylar pole (n = 20). Condylar deformations in these cases were similar to the high condylar process group, whereas diacapitular fractures not affecting the lateral condylar pole (n = 22) had better radiological results. Axiographic tracings of TMJ movements in all groups as well as clinical functional analysis demonstrated highly satisfactory functional results within physiological limits. Compared to data referring to individuals treated conservatively, far fewer irregularities of axiographic tracings were observed in this group. Limitations of condylar movements nevertheless were found frequently in the high condylar process group (35%). As a severe complication, permanent facial nerve palsies occurred in six individuls due to the preauricular approach employed. After a modification using a temporal extension, only one minor partial lesion occurred in 97 operations.

Adolescent↗

PubMed1999

[Quality of life research in patients with cleft lip and palate: preliminary results].

While esthetic and functional outcomes of treatment have improved for patients with cleft lip and palate (CLP), a CLP remains a severe problem for patients and relatives. To date, psychological research has dealt with issues such as intelligence, self-consciousness or treatment satisfaction but the long-term impact of a CLP on a psychological construct such as quality of life has yet to be explored. From a pool of 156 patients with CLP, subgroups of varying sizes were examined with a set of standardized questionnaires (KINDL, SF-36, Social Support Survey). In all patients, primary operative treatment had been accomplished. Long-term impact of the CLP on family life was assessed by 112 of the patients' parents by filling in the Impact on Family Scale. A set of questionnaires, especially developed for patients with CLP, was administered as well. For all patients who have been being treated in an interdisciplinary cleft center for their entire life, the results presented indicate that quality of life is good and within a normal range. Social support appears to be within a normal range. Parents report only minor long-term impact of the CLP on family life and family planning. Treatment satisfaction is high in the CLP patients. The questionnaires especially aimed at CLP patients indicate more specific problems mainly concerning social acceptance, where patients think the CLP had a negative impact. The standardized questionnaires employed so far failed to capture these problems. The combination of the two types of questionnaires is a sufficiently sensitive assessment procedure.

Adolescent↗

PubMed1999

[Speech rate of compensatory articulation in patients with cleft lip and palate].

Infolge eines primären Defizits der velopharyngealen Funktion liegen bei vielen Patienten mit Lippen-Kiefer-Gaumenspalten sekundäre kompensatorische Lautbildungen vor. Mit zwei neuen Computerprogrammen werden die Auswirkungen der kompensatorischen Artikulation auf die durchschnittliche Sprechgeschwindigkeit von 146 Patienten mit Lippen-Kiefer-Gaumen-spalten untersucht. Die Patienten wurden dabei nach dem Schweregrad der artikulatorischen Auffälligkeit gruppiert. Bei der schnellen Silbenwiederholung zeigte sich, dass die durchschnittliche Silbenrate pro Sekunde bei Patienten mit deutlich auffälliger Artikulation signifikant reduziert war. Beim Nachsprechen von Sätzen war die zum Nachsprechen benötigte Gesamtzeit bei dieser Patientengruppe signifikant erhöht, und das Zielwort des Satzes wurde signifikant später begonnen. Die Ergebnisse zeigen, dass die mittlere Sprechgeschwindigkeit von Patienten mit Lippen-Kiefer-Gaumenspalten mit kompensatorischer palatolalischer Artikulation niedriger ist.

Adolescent↗

PubMed1998

Bactericidal action of 308 nm excimer-laser radiation: an in vitro investigation.

The aim of the present study was to investigate the influence of 308 nm excimer-laser radiation on bacterial growth. Six different bacterial strains (Staphylococcus aureus, Escherichia coli, Streptococcus faecalis, Lactococcis lactis, Salmonella typhimurium, and Deinococcus radiodurans) were exposed in vitro to various doses and energy densities of laser radiation. To exclude bacterial killing by supraphysiological heating, the temperature change in the samples during irradiation was measured. Extended antimicrobial effects of XeCl excimer-laser radiation depending on the time of radiation, the energy density of the laser beam, and the irradiated bacterial strain were observed. Reduction of bacterial growth is independent of temperature and not linked to any ablative tissue removal. In almost all cases, a 99.9% reduction of bacteria was reached by total radiation times < 100 ms. The proven antimicrobial effects of 308 nm excimer-laser radiation may be of significant clinical importance in endodontics and periodontology in the future.

Analysis of Variance↗

PubMed1998

[Tooth injury during intubation--diagnostic and therapeutic aspects].

This study analysis 16 cases of dental injuries occurring during endotracheal intubation. The overall rate was 1 out of 6000 cases of intubation. As expected, the upper jaw teeth are most often involved. Partial dislocations were the most common lesion, together with dental fractures. A well-documented dental evaluation before delivery of anesthetics and appropriate precautions and protective devices during intubation will prevent most dental trauma related to endotracheal intubation. Also, early use of dental and risk management services often will ensure timely resolution of such problems.

Humans↗

PubMed1998

[Perceptive and instrumental examination of voice quality in patients with lip-jaw-palate clefts].

BACKGROUND: In Anglo-American literature, prevalences as high as 41% are reported for voice disorders in cleft lip and palate (CLP) patients. Because of considerable variability in the reported findings and because no prevalence data are available for the German-speaking area, a screening study was conducted. METHOD: 154 patients with CLP were examined. Voice quality was assessed perceptively according to the rbh-system (roughness, breathiness, hoarseness). Suprasegmentals and nasal resonance were also assessed. Using a new computer programme for the apparative analysis of voice quality, data for pitch, intensity and pertubation (jitter and shimmer) were obtained for 4 sustained vowels. RESULTS: Based on perceptual analysis, we found that the prevalence of severe voice disorders in CLP patients was 6.5% which is lower than reported in most other studies. The incidence of voice disorders in CLP patients is numerically only slightly higher than in the normal population. The acoustic measurements confirm the results of perceptual analysis. Since the prevalence of severe voice disorders was low, none of the pertubation quotients differentiated between modal and disordered voices. A weak correlation was found between jitter and the ratings for hoarseness. CONCLUSIONS: 1. While it is appropriate to assume a higher potential risk for vocal dysfunction in CLP patients the actual prevalence in the patients examined is numerically only slightly higher than in normals. 2. For patients with voice disorders, apparative diagnostics of voice quality is a useful and practical adjunct to perceptual analysis which helps profiling individual patients and helps the professional to make decisions for therapy.

Adolescent↗

PubMed1997

[Axiographic functional parameters after dysgnathia operations with special reference to the position of the temporomandibular joint].

This follow-up study was designed to identify the differences between the TMJ movements of individuals undergoing orthognathic surgery, with and without positioning of the mandibular proximal segment. A further aim was to assess the location of the terminal hinge axis before and after surgery regarding variations due to mandibular advancement or set back, respectively combined two jaw osteotomy. Mechanical axiographic tracings were documented in 14 patients undergoing orthognatic surgery without positioning of the mandibular proximal segment. The terminal hinge axis position was marked by a tattoo. After surgery two more axiographic tracings were recorded over a follow-up period of 24 months. Changes to the terminal hinge axis position were also documented. Condylar guidance angles showed no differences, whereas Bennett angles decreased by an average of 25%. Subjective or objective TMJ symptoms after surgery could be observed in 64% of the patients, compared to 50% before surgery. Considerable variations in the position of the terminal hinge axis were observed nine months after surgery, especially in the two jaw group. In Class II individuals the terminal hinge axis was found in a cranial position both after 9 and 24 months. Class III individuals with two jaw surgery also gained a long term cranial localisation, whereas Class III patients with mandibular setback only demonstrated a hinge axis position inferior and anterior compared to the preoperative reference. No statistically significant differences were apparent between the axiographic condylar movement parameters in the present group as compared to data published employing condylar positioning.

Biomechanical Phenomena↗

PubMed1997

[Precision of 3D-assisted surgical planning with rapid prototype techniques].

Our clinical results show that 3D model building is an excellent method for 3D preoperative planning. Dependent on the number of steps, however, there are many possibilities of failures. Standardization and quality control of data acquisition and industrial manufacturing must be recommended. This is especially important for stereolithography, as it is definitely more complex than the milling technique. One possibility seems to be the use of phantom models. Another factor is that the surgeon has to be involved in the essential steps of data analysis and segmentation. Based on our experience, the building of 3D CT skull models is a clinically efficient method that is mature enough for clinical use, but cannot yet be accepted as the clinical routine. Quality assurance is urgently necessary.

Equipment Design↗

PubMed1997

[Video matching as intraoperative navigation aid in operations to improve the facial profile].

Planning and simulation of individual interventions are not yet the common standard treatment in general surgery. Improvements in planning and simulation of individual orthognatic and craniofacial interventions have led to the need to transfer the results of preoperative planning to the location. Videomatching offers a new approach to the surgeon so that simulation output can be used in a highly intuitive way. Congruent video superimposition of the real site and a view of the simulation give the surgeon a unified view of both domains. Visual merging is immediately accepted by the surgeon who prefers the intuitive, non-tactile nature of this highly informative navigational aid. Application and positioning of anatomical markers and time-consuming calibration procedures can be reduced to a minimum. Alternative plans can be discussed among several surgeons preoperatively, and different therapeutic concepts solidified in various simulation models can be selected intraoperatively. We concentrate on the application of this new method in craniomaxillofacial surgery, but it is applicable in other disciplines as well.

Calibration↗